Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commer... more Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commersonii, found along southern South America (SA) and the Falkland Islands/Islas Malvinas (FI/IM), and C. c. kerguelenensis, restricted to the subantarctic Kerguelen Islands (KI). Following the dispersal model proposed for the genus, the latter is thought to have originated from SA after a long-distance dispersal event. To evaluate this biogeographic scenario, a distribution-wide, balanced sampling of mitochondrial DNA (mtDNA) control region sequences was designed. New tissue samples from southern Chile, Argentina, FI/IM, and KI were added to published sequences from SA and KI, for a total of 256 samples. Genetic diversity indices, genetic and phylogeographic structure, and migration rates were calculated. One haplotype was shared between subspecies, with which all haplotypes of C. c. kerguelenensis formed a distinct group in the haplotype network. A new haplotype for C. c. kerguelenensis i...
HAL (Le Centre pour la Communication Scientifique Directe), Apr 14, 2010
The high proportion of brooding (50 to 70% depending on phyla) compared with broadcaster species ... more The high proportion of brooding (50 to 70% depending on phyla) compared with broadcaster species among invertebrates living along the coast of the Southern ocean has been traditionally interpreted as an adaptation to local environmental conditions. Currently, however, species with a planktotrophic developmental mode are ecologically dominant along coastal areas, in terms of abundance of individuals. The fact that Kerguelen island is inhabited by such species and that the French base Port-aux-Français, with its equipped marine laboratory, made it possible to address questions as to why are there so many brooders in the coastal waters of the Southern ocean and if the apparent ecological success of broadcasters related to their developmental mode. We argue that the present shallow antarctic benthic invertebrate fauna is the result of two processes acting at different temporal scales. First, the high proportion of brooding species compared with coastal communities elsewhere corresponds to species-level selection occurring over geological and evolutionary times which explains the very high biodiversity observed in coastal waters. Second, the ecological dominance of broadcasters is the result of processes operating at ecological timescales that are associated with the advantage of having pelagic larvae under highly disturbed conditions (e.g., ice scouring). rÉsUMÉ.-les îles Kerguelen : un laboratoire vivant pour la compréhension de la biodiversité benthique en antarctique. la proportion élevée (50 à 70% selon les phylums) d'espèces incubantes comparée à celle des espèces dispersantes d'invertébrés vivant dans les eaux côtières de l'océan austral a été traditionnellement interprétée comme une adaptation aux conditions environnementales locales. Cependant, de nos jours, les espèces à développement planctotrophique y sont écologiquement dominantes, en termes d'abondance. le fait que les îles Kerguelen abritent de telles espèces et que la base de Port-aux-Français possède un véritable laboratoire marin a permis de développer des programmes pour répondre à des questions comme : pourquoi y-at -il tant d'espèces incubantes dans les eaux côtières de l'océan austral ? ou bien, le succès écologique apparent des espèces dispersantes est-il lié à leur mode de développement ? nous soutenons que la faune actuelle d'invertébrés benthiques côtiers antarctiques est le résultat de deux processus agissant à des échelles temporelles différentes : (1) la proportion élevée d'espèces incubantes, comparée aux communautés côtières partout ailleurs, correspond à une sélection au niveau de l'espèce se produisant à des échelles de temps géologiques qui explique la biodiversité très élevée observée dans les eaux côtières, (2) la dominance écologique actuelle des espèces dispersantes est le résultat de processus fonctionnant à des échelles de temps écologiques qui sont associés à l'avantage de posséder des larves pélagiques dans des conditions fortement perturbées (p. ex., rabotage des fonds par les icebergs).
The complementarity of historical and contemporary processes contributes to understanding the gen... more The complementarity of historical and contemporary processes contributes to understanding the genetic structure of continuously distributed marine species with high dispersal capabilities. Cephalorhynchus eutropia, has a continuous coastal distribution with strong genetic differentiation identified by nuclear DNA markers. We explored the historical dimension of this genetic differentiation between northern and southern populations to evaluate phylogeographic structure. Additionally, we conducted mtDNA and microsatellite analyses to detect past and recent demographic changes. The southern population was characterized by lower genetic diversity with a signal of population expansion, likely associated with ice retreat and habitat extension after the Last Glacial Maximum (LGM). In contrast, structure within the northern population was more consistent with stable historical population size. Approximate Bayesian Computation analyses suggested that during the LGM, C. eutropia persisted in ...
Climatic and oceanographic events occurring during the last glacial cycle in the Humboldt Current... more Climatic and oceanographic events occurring during the last glacial cycle in the Humboldt Current System (HCS) have left genetic footprints in marine invertebrate populations. The objective of this study was to evaluate the effect of the glacial period on Octopus mimus populations found throughout the HCS. This species lays a large number of small eggs which hatch into planktonic paralarvae with the potential to undergo wide dispersal. We sequenced the COIII gene to perform phylogeographic analyses of 197 octopuses sampled from seven localities. The genetic diversity of Octopus mimus was low and decreased towards the southern end of the distribution range, which comprises a single population. The haplotype genealogy and Bayesian Skyride plot suggest that O. mimus underwent a demographic expansion after the last glacial maximum (LGM). This would imply a contraction of the range of this organism toward northern latitudes during the LGM followed by southward expansion and recolonization once the contemporary interglacial period began.
... ISBN 90 5410596 8 Genetic differentiation of Echinocardium cor datum as revealed by allozymes... more ... ISBN 90 5410596 8 Genetic differentiation of Echinocardium cor datum as revealed by allozymes and RNA sequencing Jean-Pierre Feral, Elie Poulin, Evelyne Derelle, Sylvie Gallardo & Cecile Chambon Observatoire Oceanologique, Universite Pierre el Marie Curie, CNRS ...
Journal of Experimental Marine Biology and Ecology, Feb 1, 2001
Traditional classifications of developmental patterns of marine benthic invertebrates are based o... more Traditional classifications of developmental patterns of marine benthic invertebrates are based on combinations of embryological (direct or indirect development) and ecological (such as nutritional source or habitat) characteristics. Different schemes have been proposed for different reasons, relating to ecology, evolution and / or development. However, these classifications contain interconnected characters that do not efficiently discriminate between developmental patterns and, thus, do not fully apply to either ecological or embryological studies. An ecological multifactor classification based on three independent two-state characters (pelagic / benthic, free / protected, and feeding / non-feeding) is proposed. It discriminates between eight developmental patterns and can encompass any ecological pattern of development among marine benthic invertebrates.
This study examined the spatial distribution at different geographic scales of the echinoid Abatu... more This study examined the spatial distribution at different geographic scales of the echinoid Abatus cordatus which is endemic to the Kerguelen Islands. Special attention was paid to the nondispersal strategy of the specles. It lives burrowed in the sediment and females brood t h e~r young in dorsal pouches. The dispersal of this species is therefore characterised by a limited mobility among adults and the lack of a free-swimming larval phase. Using SCUBA and dredging, A. cordatus was sampled all around Kerguelen. The spatial distribution from the island scale to the bay scale shows discontinuities at 2 levels: (1) at the island level favourable sectors (princ~pally characterised by jagged coastline with numerous sheltered bays) are separated by linear coastline or swell exposed sectors; (2) at the bay scale A. cordatus lives in high density, isolated demes in shallow water of sheltered bays. A. cordatus was most numerous in sediments that ranged from medium to fine sand. The granulometry of the sed~ment and the lack of predation determine this aggregated spatial distrlbution pattern. Considering that the scale of larval dispersal is the consequence of spatial and temporal habitat structure, the non-dispersal strategy of A. cordatus is associated with a spatially varying but temporally constant habitat as predicted by theoretical models.
HAL (Le Centre pour la Communication Scientifique Directe), 1997
The coastal echinoids found at Terre Adélie belong to two trophic groups. Herbivores are represen... more The coastal echinoids found at Terre Adélie belong to two trophic groups. Herbivores are represented by the regular sea urchin, Sterechinus neumayeri, and deposit-feeders by three sympatric brooding species of Abatus. The coexistence of the latter is viewed in relation to long-term évolution of the clade, especially to brood protection, on the background of the tectonic and climatic history of the Antarctic continent. RÉSUMÉ.-Les oursins côtiers de Terre Adélie appartiennent à deux groupes trophiques. Les herbivores sont représentés par l'oursin régulier, Sterechinus neumayeri, les détritivores par trois espèces incubantes sympatriques du genre Abatus. La coexistence de ces dernières semble surtout liée à l'évolution à long terme du clade en relation avec le phénomène d'incubation et avec l'histoire tectonique et climatique du continent Antarctique.
Sterechinus is a very common echinoid genus in benthic communities of the Southern Ocean. It is w... more Sterechinus is a very common echinoid genus in benthic communities of the Southern Ocean. It is widely distributed across the Antarctic and South Atlantic Oceans and has been the most frequently collected and intensively studied Antarctic echinoid. Despite the abundant literature devoted to Sterechinus, few studies have questioned the systematics of the genus. Sterechinus bernasconiae is the only species of Sterechinus reported from the Pacific Ocean and is only known from the few specimens of the original material. Based on new material collected during the oceanographic cruise INSPIRE on board the R/V Melville, the taxonomy and phylogenetic position of the species are revised. Molecular and morphological analyses show that S. bernasconiae is a subjective junior synonym of Gracilechinus multidentatus (Clark). Results also show the existence of two genetically distinct subclades within the so-called Sterechinus clade: a Sterechinus neumayeri subclade and a subclade composed of other Sterechinus species. The three nominal species Sterechinus antarcticus, Sterechinus diadema, and Sterechinus agassizi cluster together and cannot be distinguished. The species Sterechinus dentifer is weakly differentiated from these three nominal species. The elucidation of phylogenetic relationships between G. multidentatus and species of Sterechinus also allows for clarification of respective biogeographic distributions and emphasizes the putative role played by biotic exclusion in the spatial distribution of species.
One of the current challenges in today's ecology research is to understand and quantify the effec... more One of the current challenges in today's ecology research is to understand and quantify the effects of climate changes on biodiversity. In order to detect possible trends in biodiversity patterns, it is necessary to conduct longterm observations in various and representative environments. This is always challenging, even more difficult in marine habitats and in the Southern Ocean in particular. Since 2012, a submarine observatory of the coastal benthos has been in operation in the Kerguelen Islands. Eight contrasting sites are monitored using photo and video surveys, loggers, and settlement plots. To quantify potential changes, several photographic analysis techniques are also complemented by scuba diving and ROV (Remotely Operated Vehicle) observations. Investigator scientists have developed and improved new protocols that will be carried out in the long term by the staff of the National Natural Reserve of the French Southern Territories. In order to provide reliable support of species identification, the Proteker program supported by IPEV, French Polar Institute, is currently developing several field guides that should improve the identification of the main taxa being monitored. In light of their abundance in coastal environments of the Kerguelen Islands, and because they are among the most visible invertebrates and the easiest of organisms to consider for monitoring surveys, we first focused on echinoderms. Results of this first study are presented here. For each echinoderm species, a spreadsheet provides the species name with synonymies, a description of diagnostic features, the recorded distribution, as well as three different types of illustrations: (i) living specimens in their environment, which is useful for scuba divers, (ii) fresh collected specimens out of water, and (iii) specimens fixed in ethanol. Therefore, species can be identified alive while diving, but also after sampling in the field, and after several years in the laboratory. An assessment of Kerguelen's coastal echinoderms is also given.
Proceedings of the Royal Society B: Biological Sciences
Molecular-based analysis has become a fundamental tool to understand the role of Quaternary glaci... more Molecular-based analysis has become a fundamental tool to understand the role of Quaternary glacial episodes. In the Magellan Province in southern South America, ice covering during the last glacial maximum (20 ka) radically altered the landscape/seascape, speciation rates and distribution of species. For the notothenioid fishes of the genus Harpagifer, in the area are described two nominal species. Nevertheless, this genus recently colonized South America from Antarctica, providing a short time for speciation processes. Combining DNA sequences and genotyping-by-sequencing SNPs, we evaluated the role of Quaternary glaciations over the patterns of genetic structure in Harpagifer across its distribution in the Magellan Province. DNA sequences showed low phylogeographic structure, with shared and dominant haplotypes between nominal species, suggesting a single evolutionary unit. SNPs identified contrastingly two groups in Patagonia and a third well-differentiated group in the Falkland/...
Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that fact... more Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that factors such as climate, food availability, and environmental pressures that produce high levels of stress can exert a strong influence on mitochondrial genomes, to the point of promoting the persistence of certain genotypes in order to compensate for the metabolic requirements of the local environment. As recently discovered, the gentoo penguins (Pygoscelis papua) comprise four highly divergent lineages across their distribution spanning the Antarctic and sub-Antarctic regions. Gentoo penguins therefore represent a suitable animal model to study adaptive processes across divergent environments. Based on 62 mitogenomes that we obtained from nine locations spanning all four gentoo penguin lineages, we demonstrated lineage-specific nucleotide substitutions for various genes, but only lineage-specific amino acid replacements for the ND1 and ND5 protein-coding genes. Purifying selection (dN/dS &...
In the Kerguelen Islands, the multiple effects of climate change are expected to impact coastal m... more In the Kerguelen Islands, the multiple effects of climate change are expected to impact coastal marine habitats. Species distribution models (SDM) can represent a convenient tool to predict the biogeographic response of species to climate change but biotic interactions are not considered in these models. Nevertheless, new species interactions can emerge in communities exposed to environmental changes and the structure of biotic interactions is directly related to the potential resilience of ecosystems. Trophic interaction studies can help predict species vulnerability to environmental changes using carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope ratios to generate trophic models. Using new available data inputs, we generated robust SDM and trophic interaction models to assess the potential response and sensitivity of three echinoid species to future worst-case scenarios of environmental change in the Kerguelen Plateau region. The two modelling approaches provide contrasting ins...
In the current context of climate change, sea-surface temperature variation, sea level rise and l... more In the current context of climate change, sea-surface temperature variation, sea level rise and latitudinal shifts of currents and hydrological fronts are expected to affect marine biodiversity of the sub-Antarctic Islands, particularly in coastal waters. Characterising the impacts of climate change on marine communities requires recording environmental modifications through the establishment of long-term monitoring. PROTEKER aims at the establishment of a submarine observatory consisting of multi-disciplinary research: oceanography, habitat mapping and species inventories, genetic, eco-physiological and trophic analyses. It also aims to provide scientific standards for the management of the Kerguelen Marine Reserve. Eighteen sampling sites of previous programs were revisited by scuba diving among which eight were selected for monitoring and were progressively equipped. ROV observations and beam trawling have also been conducted for contextualisation. These sites (Morbihan Bay (4), ...
Most of the microbial biogeographic patterns in the oceans have been depicted at the whole commun... more Most of the microbial biogeographic patterns in the oceans have been depicted at the whole community level, leaving out finer taxonomic resolution (i.e., microdiversity) that is crucial to conduct intra-population phylogeographic study, as commonly done for macroorganisms. Here, we present a new approach to unravel the bacterial phylogeographic patterns combining community-wide survey by 16S rRNA gene metabarcoding and intra-species resolution through the oligotyping method, allowing robust estimations of genetic and phylogeographic indices, and migration parameters. As a proof-of-concept, we focused on the bacterial genusSpirochaetaacross three distant biogeographic provinces of the Southern Ocean; maritime Antarctica, sub-Antarctic Islands, and Patagonia. Each targetedSpirochaetaoperational taxonomic units were characterized by a substantial intrapopulation microdiversity, and significant genetic differentiation and phylogeographic structure among the three provinces. Gene flow es...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commer... more Commerson’s dolphins (Cephalorhynchus commersonii) are separated into the subspecies C. c. commersonii, found along southern South America (SA) and the Falkland Islands/Islas Malvinas (FI/IM), and C. c. kerguelenensis, restricted to the subantarctic Kerguelen Islands (KI). Following the dispersal model proposed for the genus, the latter is thought to have originated from SA after a long-distance dispersal event. To evaluate this biogeographic scenario, a distribution-wide, balanced sampling of mitochondrial DNA (mtDNA) control region sequences was designed. New tissue samples from southern Chile, Argentina, FI/IM, and KI were added to published sequences from SA and KI, for a total of 256 samples. Genetic diversity indices, genetic and phylogeographic structure, and migration rates were calculated. One haplotype was shared between subspecies, with which all haplotypes of C. c. kerguelenensis formed a distinct group in the haplotype network. A new haplotype for C. c. kerguelenensis i...
HAL (Le Centre pour la Communication Scientifique Directe), Apr 14, 2010
The high proportion of brooding (50 to 70% depending on phyla) compared with broadcaster species ... more The high proportion of brooding (50 to 70% depending on phyla) compared with broadcaster species among invertebrates living along the coast of the Southern ocean has been traditionally interpreted as an adaptation to local environmental conditions. Currently, however, species with a planktotrophic developmental mode are ecologically dominant along coastal areas, in terms of abundance of individuals. The fact that Kerguelen island is inhabited by such species and that the French base Port-aux-Français, with its equipped marine laboratory, made it possible to address questions as to why are there so many brooders in the coastal waters of the Southern ocean and if the apparent ecological success of broadcasters related to their developmental mode. We argue that the present shallow antarctic benthic invertebrate fauna is the result of two processes acting at different temporal scales. First, the high proportion of brooding species compared with coastal communities elsewhere corresponds to species-level selection occurring over geological and evolutionary times which explains the very high biodiversity observed in coastal waters. Second, the ecological dominance of broadcasters is the result of processes operating at ecological timescales that are associated with the advantage of having pelagic larvae under highly disturbed conditions (e.g., ice scouring). rÉsUMÉ.-les îles Kerguelen : un laboratoire vivant pour la compréhension de la biodiversité benthique en antarctique. la proportion élevée (50 à 70% selon les phylums) d'espèces incubantes comparée à celle des espèces dispersantes d'invertébrés vivant dans les eaux côtières de l'océan austral a été traditionnellement interprétée comme une adaptation aux conditions environnementales locales. Cependant, de nos jours, les espèces à développement planctotrophique y sont écologiquement dominantes, en termes d'abondance. le fait que les îles Kerguelen abritent de telles espèces et que la base de Port-aux-Français possède un véritable laboratoire marin a permis de développer des programmes pour répondre à des questions comme : pourquoi y-at -il tant d'espèces incubantes dans les eaux côtières de l'océan austral ? ou bien, le succès écologique apparent des espèces dispersantes est-il lié à leur mode de développement ? nous soutenons que la faune actuelle d'invertébrés benthiques côtiers antarctiques est le résultat de deux processus agissant à des échelles temporelles différentes : (1) la proportion élevée d'espèces incubantes, comparée aux communautés côtières partout ailleurs, correspond à une sélection au niveau de l'espèce se produisant à des échelles de temps géologiques qui explique la biodiversité très élevée observée dans les eaux côtières, (2) la dominance écologique actuelle des espèces dispersantes est le résultat de processus fonctionnant à des échelles de temps écologiques qui sont associés à l'avantage de posséder des larves pélagiques dans des conditions fortement perturbées (p. ex., rabotage des fonds par les icebergs).
The complementarity of historical and contemporary processes contributes to understanding the gen... more The complementarity of historical and contemporary processes contributes to understanding the genetic structure of continuously distributed marine species with high dispersal capabilities. Cephalorhynchus eutropia, has a continuous coastal distribution with strong genetic differentiation identified by nuclear DNA markers. We explored the historical dimension of this genetic differentiation between northern and southern populations to evaluate phylogeographic structure. Additionally, we conducted mtDNA and microsatellite analyses to detect past and recent demographic changes. The southern population was characterized by lower genetic diversity with a signal of population expansion, likely associated with ice retreat and habitat extension after the Last Glacial Maximum (LGM). In contrast, structure within the northern population was more consistent with stable historical population size. Approximate Bayesian Computation analyses suggested that during the LGM, C. eutropia persisted in ...
Climatic and oceanographic events occurring during the last glacial cycle in the Humboldt Current... more Climatic and oceanographic events occurring during the last glacial cycle in the Humboldt Current System (HCS) have left genetic footprints in marine invertebrate populations. The objective of this study was to evaluate the effect of the glacial period on Octopus mimus populations found throughout the HCS. This species lays a large number of small eggs which hatch into planktonic paralarvae with the potential to undergo wide dispersal. We sequenced the COIII gene to perform phylogeographic analyses of 197 octopuses sampled from seven localities. The genetic diversity of Octopus mimus was low and decreased towards the southern end of the distribution range, which comprises a single population. The haplotype genealogy and Bayesian Skyride plot suggest that O. mimus underwent a demographic expansion after the last glacial maximum (LGM). This would imply a contraction of the range of this organism toward northern latitudes during the LGM followed by southward expansion and recolonization once the contemporary interglacial period began.
... ISBN 90 5410596 8 Genetic differentiation of Echinocardium cor datum as revealed by allozymes... more ... ISBN 90 5410596 8 Genetic differentiation of Echinocardium cor datum as revealed by allozymes and RNA sequencing Jean-Pierre Feral, Elie Poulin, Evelyne Derelle, Sylvie Gallardo & Cecile Chambon Observatoire Oceanologique, Universite Pierre el Marie Curie, CNRS ...
Journal of Experimental Marine Biology and Ecology, Feb 1, 2001
Traditional classifications of developmental patterns of marine benthic invertebrates are based o... more Traditional classifications of developmental patterns of marine benthic invertebrates are based on combinations of embryological (direct or indirect development) and ecological (such as nutritional source or habitat) characteristics. Different schemes have been proposed for different reasons, relating to ecology, evolution and / or development. However, these classifications contain interconnected characters that do not efficiently discriminate between developmental patterns and, thus, do not fully apply to either ecological or embryological studies. An ecological multifactor classification based on three independent two-state characters (pelagic / benthic, free / protected, and feeding / non-feeding) is proposed. It discriminates between eight developmental patterns and can encompass any ecological pattern of development among marine benthic invertebrates.
This study examined the spatial distribution at different geographic scales of the echinoid Abatu... more This study examined the spatial distribution at different geographic scales of the echinoid Abatus cordatus which is endemic to the Kerguelen Islands. Special attention was paid to the nondispersal strategy of the specles. It lives burrowed in the sediment and females brood t h e~r young in dorsal pouches. The dispersal of this species is therefore characterised by a limited mobility among adults and the lack of a free-swimming larval phase. Using SCUBA and dredging, A. cordatus was sampled all around Kerguelen. The spatial distribution from the island scale to the bay scale shows discontinuities at 2 levels: (1) at the island level favourable sectors (princ~pally characterised by jagged coastline with numerous sheltered bays) are separated by linear coastline or swell exposed sectors; (2) at the bay scale A. cordatus lives in high density, isolated demes in shallow water of sheltered bays. A. cordatus was most numerous in sediments that ranged from medium to fine sand. The granulometry of the sed~ment and the lack of predation determine this aggregated spatial distrlbution pattern. Considering that the scale of larval dispersal is the consequence of spatial and temporal habitat structure, the non-dispersal strategy of A. cordatus is associated with a spatially varying but temporally constant habitat as predicted by theoretical models.
HAL (Le Centre pour la Communication Scientifique Directe), 1997
The coastal echinoids found at Terre Adélie belong to two trophic groups. Herbivores are represen... more The coastal echinoids found at Terre Adélie belong to two trophic groups. Herbivores are represented by the regular sea urchin, Sterechinus neumayeri, and deposit-feeders by three sympatric brooding species of Abatus. The coexistence of the latter is viewed in relation to long-term évolution of the clade, especially to brood protection, on the background of the tectonic and climatic history of the Antarctic continent. RÉSUMÉ.-Les oursins côtiers de Terre Adélie appartiennent à deux groupes trophiques. Les herbivores sont représentés par l'oursin régulier, Sterechinus neumayeri, les détritivores par trois espèces incubantes sympatriques du genre Abatus. La coexistence de ces dernières semble surtout liée à l'évolution à long terme du clade en relation avec le phénomène d'incubation et avec l'histoire tectonique et climatique du continent Antarctique.
Sterechinus is a very common echinoid genus in benthic communities of the Southern Ocean. It is w... more Sterechinus is a very common echinoid genus in benthic communities of the Southern Ocean. It is widely distributed across the Antarctic and South Atlantic Oceans and has been the most frequently collected and intensively studied Antarctic echinoid. Despite the abundant literature devoted to Sterechinus, few studies have questioned the systematics of the genus. Sterechinus bernasconiae is the only species of Sterechinus reported from the Pacific Ocean and is only known from the few specimens of the original material. Based on new material collected during the oceanographic cruise INSPIRE on board the R/V Melville, the taxonomy and phylogenetic position of the species are revised. Molecular and morphological analyses show that S. bernasconiae is a subjective junior synonym of Gracilechinus multidentatus (Clark). Results also show the existence of two genetically distinct subclades within the so-called Sterechinus clade: a Sterechinus neumayeri subclade and a subclade composed of other Sterechinus species. The three nominal species Sterechinus antarcticus, Sterechinus diadema, and Sterechinus agassizi cluster together and cannot be distinguished. The species Sterechinus dentifer is weakly differentiated from these three nominal species. The elucidation of phylogenetic relationships between G. multidentatus and species of Sterechinus also allows for clarification of respective biogeographic distributions and emphasizes the putative role played by biotic exclusion in the spatial distribution of species.
One of the current challenges in today's ecology research is to understand and quantify the effec... more One of the current challenges in today's ecology research is to understand and quantify the effects of climate changes on biodiversity. In order to detect possible trends in biodiversity patterns, it is necessary to conduct longterm observations in various and representative environments. This is always challenging, even more difficult in marine habitats and in the Southern Ocean in particular. Since 2012, a submarine observatory of the coastal benthos has been in operation in the Kerguelen Islands. Eight contrasting sites are monitored using photo and video surveys, loggers, and settlement plots. To quantify potential changes, several photographic analysis techniques are also complemented by scuba diving and ROV (Remotely Operated Vehicle) observations. Investigator scientists have developed and improved new protocols that will be carried out in the long term by the staff of the National Natural Reserve of the French Southern Territories. In order to provide reliable support of species identification, the Proteker program supported by IPEV, French Polar Institute, is currently developing several field guides that should improve the identification of the main taxa being monitored. In light of their abundance in coastal environments of the Kerguelen Islands, and because they are among the most visible invertebrates and the easiest of organisms to consider for monitoring surveys, we first focused on echinoderms. Results of this first study are presented here. For each echinoderm species, a spreadsheet provides the species name with synonymies, a description of diagnostic features, the recorded distribution, as well as three different types of illustrations: (i) living specimens in their environment, which is useful for scuba divers, (ii) fresh collected specimens out of water, and (iii) specimens fixed in ethanol. Therefore, species can be identified alive while diving, but also after sampling in the field, and after several years in the laboratory. An assessment of Kerguelen's coastal echinoderms is also given.
Proceedings of the Royal Society B: Biological Sciences
Molecular-based analysis has become a fundamental tool to understand the role of Quaternary glaci... more Molecular-based analysis has become a fundamental tool to understand the role of Quaternary glacial episodes. In the Magellan Province in southern South America, ice covering during the last glacial maximum (20 ka) radically altered the landscape/seascape, speciation rates and distribution of species. For the notothenioid fishes of the genus Harpagifer, in the area are described two nominal species. Nevertheless, this genus recently colonized South America from Antarctica, providing a short time for speciation processes. Combining DNA sequences and genotyping-by-sequencing SNPs, we evaluated the role of Quaternary glaciations over the patterns of genetic structure in Harpagifer across its distribution in the Magellan Province. DNA sequences showed low phylogeographic structure, with shared and dominant haplotypes between nominal species, suggesting a single evolutionary unit. SNPs identified contrastingly two groups in Patagonia and a third well-differentiated group in the Falkland/...
Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that fact... more Although mitochondrial DNA has been widely used in phylogeography, evidence has emerged that factors such as climate, food availability, and environmental pressures that produce high levels of stress can exert a strong influence on mitochondrial genomes, to the point of promoting the persistence of certain genotypes in order to compensate for the metabolic requirements of the local environment. As recently discovered, the gentoo penguins (Pygoscelis papua) comprise four highly divergent lineages across their distribution spanning the Antarctic and sub-Antarctic regions. Gentoo penguins therefore represent a suitable animal model to study adaptive processes across divergent environments. Based on 62 mitogenomes that we obtained from nine locations spanning all four gentoo penguin lineages, we demonstrated lineage-specific nucleotide substitutions for various genes, but only lineage-specific amino acid replacements for the ND1 and ND5 protein-coding genes. Purifying selection (dN/dS &...
In the Kerguelen Islands, the multiple effects of climate change are expected to impact coastal m... more In the Kerguelen Islands, the multiple effects of climate change are expected to impact coastal marine habitats. Species distribution models (SDM) can represent a convenient tool to predict the biogeographic response of species to climate change but biotic interactions are not considered in these models. Nevertheless, new species interactions can emerge in communities exposed to environmental changes and the structure of biotic interactions is directly related to the potential resilience of ecosystems. Trophic interaction studies can help predict species vulnerability to environmental changes using carbon (δ 13 C) and nitrogen (δ 15 N) stable isotope ratios to generate trophic models. Using new available data inputs, we generated robust SDM and trophic interaction models to assess the potential response and sensitivity of three echinoid species to future worst-case scenarios of environmental change in the Kerguelen Plateau region. The two modelling approaches provide contrasting ins...
In the current context of climate change, sea-surface temperature variation, sea level rise and l... more In the current context of climate change, sea-surface temperature variation, sea level rise and latitudinal shifts of currents and hydrological fronts are expected to affect marine biodiversity of the sub-Antarctic Islands, particularly in coastal waters. Characterising the impacts of climate change on marine communities requires recording environmental modifications through the establishment of long-term monitoring. PROTEKER aims at the establishment of a submarine observatory consisting of multi-disciplinary research: oceanography, habitat mapping and species inventories, genetic, eco-physiological and trophic analyses. It also aims to provide scientific standards for the management of the Kerguelen Marine Reserve. Eighteen sampling sites of previous programs were revisited by scuba diving among which eight were selected for monitoring and were progressively equipped. ROV observations and beam trawling have also been conducted for contextualisation. These sites (Morbihan Bay (4), ...
Most of the microbial biogeographic patterns in the oceans have been depicted at the whole commun... more Most of the microbial biogeographic patterns in the oceans have been depicted at the whole community level, leaving out finer taxonomic resolution (i.e., microdiversity) that is crucial to conduct intra-population phylogeographic study, as commonly done for macroorganisms. Here, we present a new approach to unravel the bacterial phylogeographic patterns combining community-wide survey by 16S rRNA gene metabarcoding and intra-species resolution through the oligotyping method, allowing robust estimations of genetic and phylogeographic indices, and migration parameters. As a proof-of-concept, we focused on the bacterial genusSpirochaetaacross three distant biogeographic provinces of the Southern Ocean; maritime Antarctica, sub-Antarctic Islands, and Patagonia. Each targetedSpirochaetaoperational taxonomic units were characterized by a substantial intrapopulation microdiversity, and significant genetic differentiation and phylogeographic structure among the three provinces. Gene flow es...
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
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Papers by Elie Poulin